Electrochemical destruction of mines



9, 1966 F. A. ROHRMAN 3,265,598 Q ELECTROCHEMICAL DESTRUCTION OF MINES Filed Aug. 4. 1960 INVENTOR FREDERICK A. ROHRMAN ATTORNEYS Unite tates "te 3,265,598 ELECTROCHEMICAL DESTRUCTION F MINES Frederick A. Rohrman, Panama City, Fla, assignor to the United States of America as represented by the Secretary of the Navy Filed Aug. 4, 1960, Ser. No. 47,565 2 Claims. (Cl. 204-141) The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

The present invention relates to mine warfare and more particularly to the sweeping of mined waters by the electrochemical destruction of mines.

An object of the invention is to provide a method and composition for the anodic destruction of metal surfaces immersed in an electrolyte.

Another object of the invention is to provide a method and composition which will bring about the perforation of a steel mine case to permit the entrance of sea water for neutralizing the mine.

Still another object of the invention is to provide for the violation of the integrity of mine casings on a mass basis.

A further object of the invention is to provide a method and means for the nonexplosive destruction in situ of mines on an areal basis without endangering personnel on ships.

Other objects and advantages of the invention will become evident to those skilled in the art from the following description of the preferred embodiment of the invention.

The threat to shipping and amphibious assaults presented by mined waters is well known and great effort has been expended without complete success to provide means and procedures for countering this threat. Mine hunting in the present state of the art is time consuming and if underwater swimmers are utilized as an adjunct thereto require an excessive number of swimmers for any minehunting operation over a realistic area. Mine sweeping is also time consuming, the sweeps must be selected to cope with diflerent influences such as magnetic, acoustic, pressure and combinations thereof and the sweep runs must be repetitive to satisfy ship-count mechanisms in the mines.

Based on the supposition that practically all mines are constructed with ferrous metal cases, the presesnt invention takes advantage of the fact that underwater corrosion of metal is electrochemical in nature and can be accelerated by electrochemical means as illustrated by the corrosion of steel when connected to copper and the corrosion of zinc when connected to steel. By making the metal case of a mine in effect a sacrificial anode by contacting it with a suitable cathodic agent, it will quickly corrode and perforate to permit quick contamination and neutralization by the entering sea water. In the accepted electrochemical theory of corrosion, a piece of iron immersed in water immediately begins to go into solution but simultaneously a chemical equivalent of hydrogen is plated out on the surface of the iron as a thin invisible film which to some extent protects the underlying iron from further action. Dissolved oxygen as it contacts this hydrogen, combines with it and slowly induces a continuous solution of the iron. This action is far too slow for any practicable means of disoslving iron. This monatomic hydrogen has a considerable resistance or overvoltage to overcome before it can be evolved as a gas; however, any electrical contact in an electrolyte of iron which is relatively high in the electrochemical series and is of a high overvoltage with that of another metal lower in the series and which is of lower overvoltage tends to break down the protection of the high overvoltage, permitting gas evolution from the second metal and greatly increasing the rate of corrosion of the iron. Only minute amounts of the second metal are needed. Palladium is the only metal known to the inventor having substantially zero overvoltage and in accordance with the invention a slightly soluble compound of palladium, preferably a fluoride, is caused to contact an elemental area of a mine casing whereby the palladium because of its favorable position in the electrochemical series plates out to provide a more cathodic material upon which a film of nascen hydrogen is plated but since palladium has substantially zero overvoltage gaseous hydrogen is vigorously evolved resulting in the most rapid type of corrosion possible and results in the perforation of a A inch steel shell in less than several hours and under optimum conditions in less than one hour.

Also in accordance with the invention a slightly soluble salt of palladium is incorporated with a water insoluble heavy organic material such as methylene chloride, aniline, acetophenone or the like capable of dissolving or perforating the paint or other protective coating on a mine case. The proportions of the palladium salt and the heavy organic vehicle in the composition are not at all critical inasmuch as their functions are performed independently and can be chosen mechanically by mixing the two in suflicient amount to provide a slurry thin enough to be dispensed in drops in the atmosphere. For example, a ratio of about /3 to A1 is suitable. The relatively high price of palladium should be of little influence in this invention because such small quantities are needed.

As illustrated in the single figure of the drawing, an airborne vehicle 10 such as a helicopter flying above the surface 11 of a body of water 12 which has been mined with booth moored mines 13 and ground mines 14 dispenses along its course the slurry in a great number of drops 15 from a suitable nozzle 16 in a fan shaped pattern normal to the planes course. These drops, which can readily be dispensed over a vast area, fall into the body of water 12 and gradually settle towards the bottom 17 being intercepted by any obstacles in the water such as the moored mines 13 and on the sea bottom 17 by the ground mines 14. If the mines 13 and 14 have no protective coating, the slightly soluble palladium salt immediately initiates its rapid corrosive action and if the mines 13 and 14 are provided with a protective coating such as paint, the heavy organic vehicle by its solvent action will remove or perforate the protective coating permitting the palladium salt to contact the iron of the mine casings. In either case, when the palladium salt contacts the iron in the presence of the sea water the electrolytic action starts with the vigorous evolution of hydrogen and in a relatively short time the mine case is perforated and the consequent flooding of the case neutralizes the mine due to the deleterious action of the sea water on its innards.

In order that the operator of the dispensing vehicle, say the helicopter pilot, may be reasonably sure of complete coverage, a suitable dye may simultaneously be spread upon the surface 11 to provide a visual indication of the area covered during each pass and this method is particuticularly useful where the sweeping operation is accomplished by two or more vehicles proceeding in echelon.

While the invention is preferably practiced using an airborne vehicle, it will be obvious that a surface vessel may be so utilized, it being remembered that such surface vessel should have a nonmetallic hull. It will also be obvious that the method of the invention may be practiced by a diver manually applying as from a collapsible tube the composition of the invention to a vulnerable area of a mine casing in those situations where nonexplosive inactivation of a mine is desired or mandatory.

While for the purpose of disclosing the invention the preferred mode of practicing it has been described in detail, it will be obvious to those skilled in the art that variations in such practice may be made without departing from the scope of the invention as defined in the appended claims.

What is claimed is:

1. The method of sweeping a mined seaway which comprises dispensing in the form of a spray on an areal basis over the surface of the seaway a composition of matter in the form of a slurry having a density greater than sea water and comprising a major portion of an insoluble liquid organic compound which is a solvent for paints and a minor portion of a slightly soluble palladium salt.

2. A composition of matter for use in the anodic perforation of ferrous metal mine casings comprising a major portion of a Water insoluble liquid organic material which is a solvent for paint and a minor portion of a slightly water soluble compound of palladium, the composition being substantially more dense than sea water.

References Cited by the Examiner JOHN H. MACK, Primary Examiner.

ROGER L. CAMPBELL, Examiner.

R. EPSTEIN, T. TUNG, Assistant Examiners. 

1. THE METHOD OF SWEEPING A MINED SEAWAY WHICH COMPRISES DISPENSING IN THE FORM OF A SPRAY ON AN AREAL BASIS OVER THE SURFACE OF THE SEAWAY A COMPOSITION OF MATTER IN THE FORM OF A SLURRY HAVING A DENSITY GREATER THAN SEA WATER AND COMPRISING A MAJOR PORTION OF AN INSOLUBLE LIQUID ORGANIC COMPOUND WHICH IS A SOLVENT FOR PAINTS AND A MINOR PORTION OF A SLIGHTLY SOLUBLE PALLADIUM SALT. 